mirror/libbpf
1
0
Fork 0
mirror of https://github.com/netdata/libbpf.git synced 2026-03-24 10:19:07 +08:00
Code Issues Packages Projects Releases Wiki Activity

libbpf: Rewrite btf datasec names starting from '?'

Browse Source 
Optional struct_ops maps are defined using question mark at the start
of the section name, e.g.:

    SEC("?.struct_ops")
    struct test_ops optional_map = { ... };

This commit teaches libbpf to detect if kernel allows '?' prefix
in datasec names, and if it doesn't then to rewrite such names
by replacing '?' with '_', e.g.:

    DATASEC ?.struct_ops -> DATASEC _.struct_ops

Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240306104529.6453-13-eddyz87@gmail.com
This commit is contained in:
Eduard Zingerman
2024-03-06 12:45:26 +02:00
committed by Andrii Nakryiko
parent fc8b86bda2
commit 438adf417d
3 changed files with 41 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

22
src/features.c
View File

@@ -147,6 +147,25 @@ static int probe_kern_btf_datasec(int token_fd)
strs, sizeof(strs), token_fd));
}
static int probe_kern_btf_qmark_datasec(int token_fd)
{
static const char strs[] = "\0x\0?.data";
/* static int a; */
__u32 types[] = {
/* int */
BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
/* VAR x */ /* [2] */
BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_VAR, 0, 0), 1),
BTF_VAR_STATIC,
/* DATASEC ?.data */ /* [3] */
BTF_TYPE_ENC(3, BTF_INFO_ENC(BTF_KIND_DATASEC, 0, 1), 4),
BTF_VAR_SECINFO_ENC(2, 0, 4),
};
return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
strs, sizeof(strs), token_fd));
}
static int probe_kern_btf_float(int token_fd)
{
static const char strs[] = "\0float";
@@ -534,6 +553,9 @@ static struct kern_feature_desc {
[FEAT_ARG_CTX_TAG] = {
"kernel-side __arg_ctx tag", probe_kern_arg_ctx_tag,
},
[FEAT_BTF_QMARK_DATASEC] = {
"BTF DATASEC names starting from '?'", probe_kern_btf_qmark_datasec,
},
};
bool feat_supported(struct kern_feature_cache *cache, enum kern_feature_id feat_id)